Filling Cracks....

[Melinda_dd]

Am I right in thinking you can fill large cracks with CA?
Do you wax the surrounding area so not to stain the surrounding wood? or just fill the crack and don't worry about over spill?
Medium ok?

Any idiot proof advice would be great as the blank in question is lovely and I really don't want to loose it/have to start my challenge entry again!

 

[CHJ]

Yes and No.

CA on its own will not have enough body on all but the finest cracks and even then it will show when finishing.

You need to fill cracks with a matching fine sanding dust and drip in thin CA, If very big then do it in stages to avoid excessive heat.

Often going for a contrast filling works better than a poor match, especially with wood containing natural features, even to the point of being creative on opening up the defect to look more random that a straight crack line.

For a Dark filling that blends well with Knots etc. I use old coffee grounds. See the Yew pieces Here (866-9)

On the CA contamination front If I think staining might be obtrusive I wipe the surface adjacent to the defect with cellulose sealer, You often get best results if you do the filling before the final few cuts, that way CA staining is removed.
If wood has natural features you can often blend in any staining on 'finished' item with a quick wipe of the area before the CA sets to give a wider and more natural spread of the stain edges.

 

[Andrewf]

I have tried using CA in the past, and have been less than impressed with the effect. Expect it works well on light coloured relatively plain timber. On highly figured wood, a load of olivewood I have been turning recently has been full of large cracks and voids. I have been using epoxy resin with a filling agent, either wood fibres, silica balloons or very fine sawdust. The epoxy tends to darken the saw dust. The advantage of epoxy resin is that it is strong and designed for use with a filler. The disadvantages are its relatively slow curing, and is susceptible to uv light, though should think that wouldn't cause too much of an issue in doors. It is also good for sticking back together bowls that have disengaged whilst turning for some reason. Several bowls turned from the olivewood have done this to me due to the voids.

 

[nev]

as with all DIY if you cant hide it, make a feature of it :mrgreen:
if the crack is ok visually (feature) and youre just worried about the inevitable explosion whilst turning, i have used gaffer tape / duct tape in the past wrapped tightly round the outside of a bowl whilst finishing the inner with light cuts and found that helps keep it together. i guess the tape allows a little flex but not a full 'pull' if theres a slight edge to catch?
(but be aware, sometimes this works toooo well and you end up going tooo thin and turning tape from the inside )

 

[Blister]

Without wanting to sound rude

How big is the crack ?

I have used 2 part epoxy resign wit either , copper , brass , aluminum powder mixed in to good effect

 

[Spindle]

Hi

Another vote for making it a feature - I like to include dried knots, voids etc. in my work - I think it adds interest and individuality.

Regards Mick

 

[Melinda_dd]

its beautiful blank so i really want to do it nice..... however i should have asked first before flooding it with ca!

think ill start another challenge bowl and take my time on this one!
can i drill out the ca already applied and start again do you think. at its deepest part its about10mm deep but only around 2mm wide. it is long though... around a 3rd of bowl circumference .

will the coffee and epoxy work? i like the idea of dark filling on the light wood. how long will it take to cure so i can turn it?

the ca method would be dust,coffee, and the ca mixed then applied?

 

[Blister]

will the coffee and epoxy work

Never tried coffee , I normally drink it :mrgreen:

 

[jumps]

I think it's been covered, but then again there's a lot of additional info...

CA has no strength, in the same way as the glass in 'fibre glass' - it will only work as a filler in conjunction with 'fibre'; wood dust works but wood shavings generally can't be packed tight enough to be subsequently impregnated.

On the other hand, and the main reason for posting, is that CA glue and a large vice/clamp may well be a solution - but it's going to create a new shape and won't be a finishing approach.

If you want to retain the shape but fill a void you need a filler, preferably with a bonding element on the basis that wood that's split may well want to split further.

 

[CHJ]

Melinda_dd , don't worry about any CA that is already in the split/crack, just fill the void with a fine powder and drip on more thin CA, pack down with a wooden coffee stirrer if necessary as it starts to go off, you'll maybe see smoke emitting. DON'T use Fingers.

If it's very big do it bit at a time, no need to mix with anything, if you look at the Dark feature on the rim of the item 869 referred to above that is 80% coffee grounds just added to a CA dampened bark inclusion and coffee grounds piled on top and further drips of CA and grounds until enough build up was achieved.

To aid the 'filler' location if it's near a rim then use masking tape to form a retainer until the CA has cured.

 

[Bodrighy]

A tip. I have bottles of dust from sanding different coloured woods, brass filings etc that I keep for filling cracks. Usually I use a mix of 2 part epoxy and the appropriate dust though it can work with CA on smaller cracks as Chas says. If you give the surrounding wood a coat of sanding sealer before using the CA glue you can sand back and leave no stain. If the crack is a big one an alternative is to widen it with a file, drill holes down each side and lace it up with wire, leather etc. Though you can disguise a crack occasionally usually it shows and it's best made into a feature IMHO.

Pete

Pete

 

[Lightweeder]

Copper powder for me. I'm always pleasantly surprised how it turns out.

 

[OldWood]

The first and only time I have used filling with CA, coffee and sawdust it was entirely successful. It was a fairly complex collection of spindle shapes on a 40mm cherry shaft and one of them ended up where there was a knot. I was able to fill the holes and turn them out and sand to a completely satisfactory finish.

The one thing I learnt was that a very small amount of coffee grains go an awful long way - fortunately it didn't matter that my fill ended up pretty black, but if you are using coffee to darken, then a small percentage to the sawdust quantity is all that is needed. As said above, pack the hole with the dry material and then dribble on the CA - thin I seem to remember - it sets immediately. My fill wasn't deep or big enough for me to worry about heat which is something I'm learning here.

Rob